Recent economic and political developments have caused an increased interest in various energy sources not previously explored or exploited on a commercial basis. One particularly promising alternative source of energy is the recovery and use of solar radiation or solar energy. Many types of solar energy conversion systems have been investigated. One of the more promising systems uses parabolic trough reflectors to concentrate the solar energy received from large area receptors in a relatively small utilization area.
Some of the most effective solar energy collectors utilize a relatively large reflector surface that is formed by constructing an elongated trough-like means with the walls of the trough having a constant parabolic shape whereby the focal points of the parabolas of the trough lie along a relatively straight line above the trough. The concave parabolic trough solar collector can be equipped with a target or energy receiver that is disposed along the line formed by the locus of focal points of the parabolic reflector. By using such a reflector means, solar radiation striking the concave surface of the solar collector will be reflected and concentrated on the focal point locus of the parabolas. The reflected radiation is captured by energy receivers located at or near the focal point locus of the parabolic surfaces.
In order to maximize the amount of solar energy that can be captured using reflector-type solar collectors, it has been found highly desirable to utilize movable solar reflector-collectors. By using the movable solar reflector-collectors as opposed to stationary collectors, the efficiency of the solar collector system can be greatly increased. Thus, the use of movable solar reflector-collectors that can be effectively aimed at the sun will greatly increase the overall energy recovery efficiency of the entire system. In the case of parabolic trough reflector solar collectors, maximum energy recovery is obtained when the axes of the parabolas of the trough walls are aimed directly at the sun. However, systems using such large movable reflector troughs are susceptible to damage from severe weather unless designed structurally to withstand weather conditions of an arbitrarily chosen high degree of severity. But often, construction of a movable reflector-collector system and its supporting structures designed to withstand weather of great severity while in any of the system operational positions is prohibitively expensive.
Many movable dish collector systems now provide means by which the collector trough or troughs can be quickly moved to a position in which they are least susceptible to damage when threatening weather conditions are detected. Nevertheless, even though the collector reflectors themselves may be to a large extent protected from damage by such positioning, it has been found that the motive drive system may sustain severe damage if it is subjected to the stress of maintaining the reflectors in their "protected" position during the periods of severe weather.